scholarly journals Linking diffuse radiation and ecosystem productivity of a desert steppe ecosystem

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9043
Author(s):  
Cheng Li ◽  
Xin Jia ◽  
Jingyong Ma ◽  
Peng Liu ◽  
Ruizhi Yang ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Diffuse Radiation ◽  
Northwest China ◽  
Desert Steppe ◽  
Ecosystem Productivity ◽  
Air Temperatures ◽  
Steppe Ecosystems ◽  
Steppe Ecosystem ◽  
Ecosystem Production ◽  
Lower Vapor Pressure

Radiation components have distinct effects on photosynthesis. In the desert steppe ecosystem, the influence of diffuse radiation on carbon fixation has not been thoroughly explored. We examined this diffusion and its effect on ecosystem productivity was examined during the growing season from 2014 to 2015 on the basis of eddy covariance measurements of CO2 exchange in a desert steppe ecosystem in northwest China. Our results indicated that the gross ecosystem production (GEP) and diffuse photosynthetically active radiation (PARdif) peaked when the clearness index (CI) was around 0.5. The maximum canopy photosynthesis (Pmax) under cloudy skies (CI < 0.7) was 23.7% greater than under clear skies (CI ≥ 0.7). When the skies became cloudy in the desert steppe ecosystem, PARdif had a greater effect on GEP. Additionally, lower vapor pressure deficits (VPD ≤ 1 kPa), lower air temperatures (Ta ≤ 20 °C), and non-stressed water conditions (REW ≥ 0.4) were more conducive for enhanced ecosystem photosynthesis under cloudy skies than under clear skies. This may be due to the comprehensive effects of VPD and Ta on stomatal conductance. We concluded that cloudiness can influence diffuse radiation components and that diffuse radiation can increase the ecosystem production of desert steppe ecosystems in northwest China.

scholarly journals The Influence Of Vegetation On Reflected Solar Radiation In Arid And Extra-Arid Zone Of Mongolian Gobi

2020 ◽  
Vol 13 (4) ◽  
pp. 72-80
Author(s):  
Viktor P. Dedkov ◽  
Elena V. Danzhalova ◽  
Sergey N. Tkachenko ◽  
S. Khadbaatar ◽  
E. Ariunbold ◽  
...  
Keyword(s):  
Solar Energy ◽  
Arid Zone ◽  
Desert Steppe ◽  
Desert Ecosystems ◽  
Noticeable Effect ◽  
Air Temperatures ◽  
Dry Steppe ◽  
Steppe Ecosystems ◽  
Infrared Wavelengths ◽  
The Difference

Vegetation cover has a noticeable effect on surface reflectivity and local microclimate in arid areas of Mongolian Gobi. Over the past decades, various shrub species (Haloxylon ammodendron and Calligonum mongolicum) have appeared on the previously unvegetated hamada. The climatic consequences of bush encroachment are still poorly understood. Using the experimental data, this article estimates the reflectance of plants dominating in Mongolia’s dry steppe, desert-steppe, and desert ecosystems. The average values of the total reflection coefficient at visible and infrared wavelengths range from 19.7% ± 1.4% to 20.1% ± 1.7% in plants growing in desert-steppe ecosystems, and from 25.0% ± 0.9% to 24.8% ± 1.5% on the bare surface. The difference between the reflectance of vegetated and unvegetated surfaces reaches 5%. Therefore, in daylight hours, the vegetated day surface loses less solar energy than the non-vegetated surface does. This phenomenon may be defined as a quasi- or secondary greenhouse effect – in daylight hours, solar energy is retained on the surface by vegetation and this contributes to the temperature increase. Such an impulse, which seems to be insignificantly small at first glance, triggers a series of climatic variations leading to a change in the structure of the radiation and heat balance as well as the climate not only in the desert-steppe and desert ecosystems but also in Central Asia as a whole. All this may explain the 1.2-2.3°C increase in air temperatures in the Gobi observed over the last 25 years.

scholarly journals Impact of Atmospheric Optical Properties on Net Ecosystem Productivity of Peatland in Poland

2021 ◽  
Vol 13 (11) ◽  
pp. 2124
Author(s):  
Kamila M. Harenda ◽  
Mateusz Samson ◽  
Radosław Juszczak ◽  
Krzysztof M. Markowicz ◽  
Iwona S. Stachlewska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Diffuse Radiation ◽  
Co2 Uptake ◽  
High Carbon ◽  
Atmospheric Scattering ◽  
Net Productivity ◽  
Diffusion Index ◽  
Ecosystem Production ◽  
The Impact ◽  
Global Carbon

Peatlands play an important role in the global carbon cycle due to the high carbon storage in the substrate. Ecosystem production depends, for example, on the solar energy amount that reaches the vegetation, however the diffuse component of this flux can substantially increase ecosystem net productivity. This phenomenon is observed in different ecosystems, but the study of the atmosphere optical properties on peatland production is lacking. In this paper, the presented methodology allowed us to disentangle the diffuse radiation impact on the net ecosystem production (NEP) of Rzecin peatland, Poland. It allowed us to assess the impact of the atmospheric scattering process determined by the aerosol presence in the air mass. An application of atmospheric radiation transfer (ART) and ecosystem production (EP) models showed that the increase of aerosol optical thickness from 0.09 to 0.17 caused NEP to rise by 3.4–5.7%. An increase of the diffusion index (DI) by 0.1 resulted in an NEP increase of 6.1–42.3%, while a DI decrease of 0.1 determined an NEP reduction of −49.0 to −10.5%. These results show that low peatland vegetation responds to changes in light scattering. This phenomenon should be taken into account when calculating the global CO2 uptake estimation of such ecosystems.

scholarly journals Distinguishing the impacts of natural and anthropogenic aerosols on global gross primary productivity through diffuse fertilization effect

2021 ◽  
Author(s):  
Hao Zhou ◽  
Xu Yue ◽  
Yadong Lei ◽  
Chenguang Tian ◽  
Jun Zhu ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Cloud Amount ◽  
Diffuse Radiation ◽  
Gross Primary Productivity ◽  
Anthropogenic Sources ◽  
Ecosystem Productivity ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Vegetation Models ◽  
Carbon Aerosols

Abstract. Aerosols can enhance ecosystem productivity by increasing diffuse radiation. Such diffuse fertilization effects (DFEs) vary among different aerosol compositions and sky conditions. Here, we apply a suite of chemical, radiation, and vegetation models in combination with ground- and satellite-based measurements to assess the impacts of natural and anthropogenic aerosol species on gross primary productivity (GPP) through DFE during 2001–2014. Globally, aerosols increase GPP by 8.9 Pg C yr-1 at clear skies but only 0.95 Pg C yr-1 at all skies. Anthropogenic aerosols account for 41% of the total GPP enhancement though they contribute only 25% to the increment of diffuse radiation. Sulfate/nitrate aerosols from anthropogenic sources make dominant contributions of 33% (36%) to aerosol DFE at all (clear) skies, followed by the ratio of 18% (22%) by organic carbon aerosols from natural sources. In contrast to other species, black carbon aerosols decrease global GPP by 0.28 (0.12) Pg C yr-1 at all (clear) skies. Long-term simulations show that aerosol DFE is increasing 2.9% yr-1 at all skies mainly because of a downward trend in cloud amount. This study suggests that the impacts of aerosols and cloud should be considered in projecting future changes of ecosystem productivity under varied emission scenarios.

Net ecosystem production in the arid land in northwest China from 1982 to 2001

2009 ◽  
Author(s):  
Shunli Chang ◽  
Qingdong Shi
Keyword(s):  
Northwest China ◽  
Net Ecosystem Production ◽  
Arid Land ◽  
Ecosystem Production

Effects of planting Caragana shrubs on soil nutrients and stoichiometries in desert steppe of Northwest China

CATENA ◽  
2019 ◽  
Vol 183 ◽  
pp. 104213 ◽  
Author(s):  
Yang Yang ◽  
Bingru Liu
Keyword(s):  
Soil Nutrients ◽  
Northwest China ◽  
Desert Steppe

Carbon dynamic simulation of desert steppe ecosystem in different climate scenarios

2020 ◽  
Vol 40 (2) ◽  
Author(s):  
王乐 WANG Le ◽  
杜灵通 DU Lingtong ◽  
丹杨 DAN Yang ◽  
宫菲 GONG Fei ◽  
郑琪琪 ZHENG Qiqi ◽  
...  
Keyword(s):  
Dynamic Simulation ◽  
Desert Steppe ◽  
Climate Scenarios ◽  
Steppe Ecosystem

Grazing exclusion significantly improves grassland ecosystem C and N pools in a desert steppe of Northwest China

CATENA ◽  
2016 ◽  
Vol 137 ◽  
pp. 441-448 ◽  
Author(s):  
Kaibo Wang ◽  
Lei Deng ◽  
Zongping Ren ◽  
Jianping Li ◽  
Zhouping Shangguan
Keyword(s):  
Northwest China ◽  
Desert Steppe ◽  
Grassland Ecosystem ◽  
Grazing Exclusion ◽  
C And N ◽  
C And N Pools

scholarly journals The seasonal abundance and its impact of temperatures on the development of life cycle of G. pecorum in Northwest China

2021 ◽  
Author(s):  
Ke Zhang ◽  
Heqing Huang ◽  
Ran Zhou ◽  
Boru Zhang ◽  
Chen Wang ◽  
...  
Keyword(s):  
Survival Rate ◽  
Population Distribution ◽  
Northwest China ◽  
Seasonal Abundance ◽  
Desert Steppe ◽  
Larval Population ◽  
Infection Period ◽  
Local Host ◽  
Arid Desert ◽  
Gasterophilus Pecorum

Abstract Background: The departure of the mature larvae of the horse stomach bot fly from the host indicates the beginning of a new infection period, and the Gasterophilus pecorum becomes the dominant species in the desert steppe, showing its special biological characteristics. The population dynamics of G. pecorum were studied to reveal the population development rule of G. pecorum in the arid desert steppe. Method: The larvae were collected and recorded in the newly excreted feces by tracking the Przewalski’s horses (Equus przewalskii), meanwhile, the larval pupation experiments were carried out under natural conditions. Results: (a) There was a positive correlation between the survival rate and the number of larvae (r = 0.630, p < 0.01), indicating that the species development had the characteristics of centralized occurrence; (b) The main periods of mature larvae discharge were from early April to early May (peak Ⅰ) and from mid-August to early September (peak II), and the larval population curve showed a sudden spike in increase and gradual decrease at both peaks; under higher temperature, the number of adults from peak II had higher survival rate, higher pupation rate, higher emergence rate and less eclosion time than that of peak I; (c) Although it has one generation a year, the occurrence peak twice annually displaying a bimodal population distribution phenomenon, which forms double parasitic pressure on the local host. This phenomenon is very rare in the study of insect life history, especially in the parasite epidemiology.Conclusion: The natural discharge period of the G. pecorum larvae in Kalamaili Nature Reserve (KNR) is longer than 7 months and have the potentially long term infection effect on the host. The above phenomenon is one important reason for the local equine animals to be severely infected with equine myiasis.

scholarly journals Carboxylation Capacity Can Limit C3 Photosynthesis at Elevated CO2 throughout Diurnal Cycles

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2603
Author(s):  
James Bunce
Keyword(s):  
Elevated Co2 ◽  
Carbon Fixation ◽  
Leaf Gas Exchange ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Early Morning ◽  
C3 Plants ◽  
Lablab Purpureus ◽  
Diurnal Cycles ◽  
Air Temperatures

The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 min using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 μmol mol−1 and one at 600 μmol mol−1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J. The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.

scholarly journals Effects of planted shrub encroachment on carbon storage of desert steppe ecosystem

2022 ◽  
Vol 42 (1) ◽  
Author(s):  
王乐，杜灵通，马龙龙，丹杨 WANG Le
Keyword(s):  
Carbon Storage ◽  
Shrub Encroachment ◽  
Desert Steppe ◽  
Steppe Ecosystem
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